Multi-State Worker Tax Fairness Act of 2014 - Prohibits a state from imposing an income tax on the compensation of a nonresident individual for any period in which such individual is not physically present in or working in such state or from deeming such nonresident individual to be present in or working in such state on the grounds that: (1) such individual is present at or working at home for convenience, or (2) such individual's work at home fails any convenience of the employer test or any similar test.